Conventionally, in a case of mixing and supplying a plurality of precursory gasses to, for example, a semiconductor process chamber, a plurality of sub-flow channels are connected to the upstream side of the main flow channel and the main flow channel is extended by several meters and connected to the process chamber. With this arrangement, the precursory gasses that flow from each flow channel are practically mixed in the main flow channel and then supplied to the process chamber.
However, if a pipe length of the main flow channel is shortened in an effort to downsize, the above-mentioned arrangement might fail to sufficiently mix the precursory gases.
For example, as shown in FIG. 16, in a case that a first fluid flows in a state of near laminar flow, the flow rate is the fastest at a center and becomes slower approaching the periphery so that the flow rate becomes almost zero near a pipe wall. Then, if a flow rate of a second fluid flowing in the pipe is small compared to the flow rate of the first fluid, the second fluid just flows slowly in proximity to the pipe wall around the first fluid so that a long period of time and a long pipe length are required for the second fluid to be mixed with the first fluid.
Then as shown in patent document 1, a helical plate is welded downstream of a portion where the sub-flow channel is connected to the main flow channel. In accordance with this arrangement, mixing of the first fluid and the second fluid can be promoted due to a stirring effect by the helical plate so that the pipe length can be shortened.
However, it takes time and costs money to join the helical plate to the pipe. In addition, for example, as shown in FIG. 15, in a case that the first fluid in the main flow channel flows in a state of a turbulent flow, since the first fluid flows back in the sub-flow channel due to a pressure difference and the second fluid has difficulty flowing into the main flow channel, the helical plate might fail to produce the effect sufficiently.